The present invention relates to a one-touch joint for a flexible tube, and more particularly, to a one-touch joint for a flexible tube, wherein said flexible tube is constituted by a corrugated tube used in gas piping, or the like.
A conventional joint for a flexible tube of this kind is disclosed, for example, in JP-A-8-159350, which describes a joint comprising: a metal tubular main body having a contact surface on the inner side thereof; a metal push ring, the end portion of which screws inside said tubular main body, in a state where a flexible tube in which a covering member is removed from several peak sections at the front end of a corrugated tube has been inserted through the push ring; and a retainer, installed at the front end of the push ring, and having metal projecting sections which are capable of engaging with the valley sections on the outer surface of the corrugated tube in the flexible tube inserted through the push ring.
In a joint for a flexible tube of this kind, by inserting the flexible tube into the push ring in a state where the push ring has provisionally been screwed loosely into the tubular main portion, the peak section at the end of the flexible tube pushes open the projecting sections of the retainer and passes by the position of these projecting sections. Thereby, when the front end of the corrugated tube projects from the end of the retainer by a prescribed amount, the projecting sections in the retainer engage with a valley section of the corrugated tube. Thereupon, by subsequently screwing in the push ring further, the end portion of the corrugated tube projecting from the end of the retainer is pressed and squeezed tightly between the projecting sections of the retainer and the contact surface of the tubular main body.
Accordingly, the flexible tube is connected to the joint in a sealed state, a seal being achieved by the squeezing of the corrugated tube by the metal sections, and hence the seal region is fire-resistant. Moreover, since the end portion of the corrugated tube is held between the projecting sections of the retainer and the contact surface of the tubular main body, this has the effect of preventing the corrugated tube from becoming detached.
However, in this joint described in JP-A-8-159350, as described above, it is necessary to perform the operation of further screwing in the push ring after the flexible tube has been inserted, and moreover, since the end portion of the corrugated tube must be pressed and squeezed as a result of this screwing operation, a relatively large amount of force is required to perform this screwing operation.
The present invention resolves these problems, an object thereof being to make it possible to connect a joint and a tube in a one-touch operation, simply by inserting a flexible tube into a joint, whilst also preventing detachment of the joint and the flexible tube, and achieving good sealing characteristics, and fire-resistant properties in the seal section.
In order to achieve this object, the one-touch joint for a flexible tube composed of a corrugated tube according to the present invention comprises: a tubular main body; a fastening ring, the front end portion of which screws inside the tubular main body, a tapered surface expanding in diameter towards the front end thereof being formed on the inner circumference of the fastening ring; a ring-shaped seal member provided inside the tubular main body; and a ring-shaped retainer located inside the tubular main body, between the tapered surface of the fastening ring and the seal member; wherein the corrugated tube of the flexible tube, the corrugated tube comprising a plurality of peak sections and valley sections, can be inserted from the end portion of the fastening ring to the inside of the fastening ring and the inside of the retainer and seal member provided in the tubular main body; and the retainer comprises: projections which project in inward radial directions at one end of the retainer; an outer circumferential surface capable of contacting the tapered surface on the inner side of the fastening ring, formed at the other end of the retainer; incisions formed in an axial direction from the one end towards the other end, in a plurality of positions along the circumference of the retainer; and a thin section, formed at the other end of the retainer, for the purpose of allowing deformation whereby the projections are pushed open elastically by a peak section of the corrugated tube when the corrugated tube is inserted into the retainer, and the projections engage with a valley section of the corrugated tube when the peak section has passed.
By adopting this composition, the flexible tube and the joint can be coupled together securely in a sealed state by means of a one-touch operation which involves simply inserting the flexible tube into the joint, without requiring any other operations, such as screwing in of members, or the like.
If a force acting to detach the flexible tube from the joint is applied thereto, the outer circumference of the retainer is pressed against the tapered surface on the inner circumference of the fastening ring, generating a reactive force acting in an inward radial direction on the projecting sections, and due to this force the projecting sections engage strongly with the valley section of the corrugated tube, thereby preventing detachment of the flexible tube.